Electro-thermal time-delay switch having a heating element and a heat-responsive switch-operating member



Feb. 27, 1968 E MARQUIS 3,371,174

ELECTRO-THERMAL TIME-DELAY swrrcn HAVING A HEATING ELEMENT AND A HEAT-RESPONSIVE SWITCH-OPERATING MEMBER 2 Sheets-Sheet 1 Filed Oct. 1, 1965 FIG. 18.

INVENTOR.

United States Patent Filed Oct. 1, 1965, Ser. No. 492,056

7 Claims. (Cl. 200-122) This invention relates to thermostatic switch devices, and more particularly to a delayed-action switch device of the type employing a heating winding acting on a heat-responsive deformable element whose deformation eventually causes operation of the switch device.

A main object of the invention is to provide a novel and improved thermal time-delay relay device which is compensated for changes in ambient temperature and which operates on the principle of thermal expansion of one portion of a body relative to other portions of the body, said one portion being initially under compression and the cooperating portion of the body being under tension, the device being very simple in construction, being compact in size, and being easy to adjust as to timing.

A further object of the invention is to provide an improved time-delay relay device of the heater type, the device being provided wit-h means to accurately adjust its timing, giving a snap action so that it operates rapidly at the end of the time delay selected for its operation, providing high contact pressure between its contacts until the point of switching thereof, thus allowing the switching of higher currents than in previously available thermal relays, providing a wiping action at its contacts as well as a snap action, whereby the contacts are kept clean, being very economical to manufacture because it employs a minimum number of parts, and being easily adaptable for use over a wide range of specified performance requirements.

A still further object of the invention is to provide an improved thermally-operated time-delay relay assembly which may be employed in conjunction with a microswitch, or other similar subsidiary switch, the relay device acting as the mechanical-operating means for the subsidiary switch device and thus, eliminating the necessity of providing a magnetic relay in conjunction therewith.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

FIGURE 1 is a vertical cross-sectional view taken through one form of thermal time-delay relay assembly constructed in accordance with the present invention.

FIGURE 2 is a vertical cross-sectional view taken substantially on the line 2-2 of FIGURE 1, but showing a modified form of heating element employed in the assembly.

FIGURE 3 is a horizontal cross-sectional view taken substantially on the line 3-3 of FIGURE 1.

FIGURE 4 is a schematic wiring diagram of the assembly of FIGURE 1, wherein "the associated switching'unit is of the single-pole, single-throw, normally-open type.

FIGURE 5 is a horizontal cross-sectional view similar to FIGURE 3, but showing a modification wherein the switching unit is of the single-pole, single-throw, normally-closed type.

FIGURE 6 is a schematic wiring diagram of the modification of the assembly illustrated in FIGURE 5.

FIGURE 7 is a horizontal cross-sectional view similar to FIGURES 3 and 5, but showing a further modification wherein the switching unit is of the single-pole, double-throw type.

FIGURE 8 is a schematic wiring diagram of the modi- 3,371,174 Patented Feb. 27, 1968 fication represented by FIGURE 7. I

FIGURE 9 is an enlarged side elevational view of the main supporting frame member of the relay, as employed in the forms of the invention illustrated in FIGURES 1 and 2.

FIGURE 10 is a front elevational view of the frame member of FIGURE 9 with a portion thereof broken away.

FIGURE 11 is an elevational view of the snap spring contact element employed in the thermal relay assembly of FIGURES 1 and 2.

FIGURE 12 is an edge view of the snap spring contact element of FIGURE 11.

FIGURE 13 is an elevational view of the attaching bracket for the snap spring element of FIGURES 11 and 12.

FIGURE 14 is an edge view of the attaching bracket shown in FIGURE 13.

FIGURE 15 is a side elevational view of a modified form of frame assembly for a thermal time-delay relay according to the present invention, employing a microswitch in conjunction with the thermally-response actuating means of the assembly.

FIGURE 16 is a side elevational view of the frame assembly of FIGURE 15.

FIGURE 17 is a vertical cross-sectional view taken substantially on the line 17-17 of FIGURE 16.

FIGURE 18 is a fragmentary vertical cross-sectional view of the lower portion of a further modification of a thermal time-delay relay constructed in accordance with the present invention, represented as of the type having normally open switch contacts.

FIGURE 19 is a fragmentary vertical cross-sectional view of the lower portion of a thermal time-delay relay similar to FIGURE 18, but represented as of the type having normally closed switch contacts.

Referring to the drawings, and more particularly to FIGURE 1, 11 generally designates one form of thermallyoperated time-delay relay assembly constructed in accordance with the present invention. The assembly 11 comprises a generally circular base 12 of suitable insulating material provided with a sealing housing or cover 13 which is secured on the circumference of the base 12 to provide a hermetically-sealed interior space. Rigidly-secured in the base 12. and extending perpendicularly thereto are a plurality of contact prongs or pins adapted to be engaged in a conventional receiving socket, the pins being circularly-arranged, as shown. Thus, seven spaced pins, numbered 14 to 20, may be provided, as shown in FIG- URE 3.

Designated at 21 is a main upstanding frame member made of suitable relatively thin malleable metal such as sheet brass, stainless steel, or any other suitable durable metal ar metal alloy, the frame member 21 being generally channel-shaped and having a rear wall 22 and respective side flanges 23 and 24 which extend parallel to each other from the opposite side edges of rear wall 22. The top end of rear wall 22 is extended to define a generally right-angled flange element 25 which projects over the enclosure defined between the two side flanges 23 and 24 and which terminates in an upstanding end tab 26, as is clearly shown in FIGURES 1, 2, 9 and 10. The end tab or flange 26 is coextensive in Width with the horizontally-extending top flange 25, said width being slightly less than the distance between the side flanges 23 or 24, the end edges of the elements 25 and 26 being inwardly-offset from the respective vertical planes of the flanges 23 and 24, as shown at 27 and 28 in FIGURE 9. Centrally-secured to flange 26 is an upstanding guide pin 26'.

The rear wall 22 is formed with an inwardly-pressed tongue element 30 which extends for the major portion of the length of rear wall 22, as shown in FIGURE 9, and which is inwardly-offset from rear wall 22 at its topconnecting portion, there being provided an arcuate transverse inWardly-offset corrugation 31 at the connection of the top end; of the tongue 30 with the top portion of the rear wall 22, as is clearly shown in FIGURE 1. The lower free end portion of tongue 30 is further provided with a forwardly-offset end tab 33. Welded or otherwise suitably connected between the upstanding top' flange element 26 and the end tab 33 is a strip 34 of the same metal as the main frame member 21, but normally in tension, the connections at the flange 26 and the tab 33 being such as to thereby place the tongue element 30 normally under compression. Thus, FIGURE shows in dotted view the normal relationship of the tongue 30 with the connection strip 34, showing the tongue 30--as being somewhat bowed. and exerting tension on the strip 34 so that the bottom tab element 33 of thetongue is located outwardly-adjacent the right side of the main frame 21. In the absence of the connection strip 34,. the tongue 30 would'assume its full-line position, as shown in FIGURE 10, which is relatively close to the plane of the rear wall 22' of the frame member 21.

Rear wall 22' is provided with the rounded bottom marginal tab 35 which is rigidly-secured, as by welding, or the like, to the upper portions of the prongs and 14. The lower endportions of the side flanges 23 and 24 are arcuat'ely notched out to define depending lug elements 38 and 39 spaced forwardly from the tab 35, said lug elements 38 and 39 being welded, or otherwise rigidlysecured to the upper portions of the respective prongs 17 and 20, as shown in FIGURE 3. Thus, the frame member 21 is rigidly-secured to and supported in upstanding position by the top end portions of the prongs 14, 15, and 17.

Secured on the strip 34, extending longitudinally thereof and in thermal contact therewith is an electrical. heating element 40 of the embedded or encased type, the

heating element 40 having the depending connection terminals 41 and 42 which are connected respectively, to the top end portions of the prongs 19' and 18. Said prongs 19 and 18, are engaged with female connectors in the associated socket which are connected in a conventional manner to a suitable energizing source, for supplying electrical energy to the heatingv element 40 when the relay device is' to be operated.

Designated generally at 43 is a generaly T-shaped sup-- porting bracket comprising the top arm 44 and the forwardly-oifset depending stem portion 45, as shown. in-

FIGURES 13 and 14. The top arm 44 is rigidly-secured, as by welding or the like, transversely to the rear wall 22 of frame element 21 with the offset stem portion 45 extending through .and inwardly-adjacent to the inside plane of rear wall 22, namely, extending through the slot defined by the forwardly-pressed tongue 30. Secured to the upper portion of stem element 45 is the top portion of a snap-contact spring member 46 provided at its lower end'portion with the contact element 47.

As shown inFIGURES 11 and 12, the snap-spring contact member 46 comprises a main body of spring metal formed. with parallel slots 48, 48 extending longitudinally for a substantial portion of the length of the body, the side portions of the body, shown at 49, 49, being crimped in the manner illustrated in FIGURE 12 so as to define the intermediate toggle leaf-spring element 50 located between the s-lots 48, 48. The leaf element 50 is normally under spring tension, and when the body 46 is bent be yond a limiting point by a force applied to the intermediate portion of the body, the. body suddenly snaps from the warped position thereof shown in FIGURE 12, 'to a reversed warped position, so that if the top portion of the body is secured, the contact button 47- suddenly travels through a substantial path of excursion. As previously mentioned, the top portion of body 46 is secured to the stationary stem portion of bracket 43, and the contact-button element 47 normally is located at a position adjacent to the bottom tab 35 of rear wall 22.

Designated at 53 is a transversely-extending stationary contact bar which is welded or otherwise rigidly-secured to the top portion of the prong 16, the contact bar 53 extending in the path of movement of the contact button 47 when the spring member 46 is snapped from the warped position thereof shown in FIGURE 1, to the reversed warped position thereof, in the manner abovedescribed. An actuating screw 55 is threadedly-engaged through the superimposed lower end portion of strip 34 and the bottom tab element 33 of tongue 30, the actuating screw 55 being adjustable, so that the time required for its inner end to engage the intermediate portion of snapspring element 46 can be adjusted; Thus, when the heating element 40 is energized, after a predetermined period of time, determined by the adjustment of screw 55, the inner end of the screw engages the intermediate portion of the snap-spring. element 46 with sufiicient force exerted on the bowed snap-spring element to cause the snap spring to reverse its contour and suddenly cause the contact button 47 to conductively engage the stationary contact bar 53-. The engagement of button 47 with bar 53 provides a wiping action, as well as a pure abutment between button 47 and bar 53, since the bar 53 is slightly yieldable and somewhat resilient. This wiping actionserves to maintain the contacting surfaces clean and to insure low-contact resistance.

Upon the deenergization of the heater element 40, the parts cool, whereby the tab 33 tends to return to its rightward: position, relieving the force on the top portion of the bowed element 50, whereby the bowed element 50 tends to resume its normal position shown in FIGURE 12, thus causing the spring member 46 to return to the normal configuration thereof illustrated in FIGURES l and 2.- This disengages contact button 47 from the contact bar 53;

It will be noted that when the strip 34 is heated by the energization of the heating element 40, the strip tends to elongate, reducing the tension therein, whereby the compression in. the tongue 30 is also reduced. The tongue 30 thus tends to hex from. the dotted-view position thereof shown in. FIGURE 10 toward the full-line position thereof, which carries the actuating screw to the left, as

viewed in FIGURE 1, so that it is engageable with theupper portion of the bowed intermediate resilient element 50 of snap-spring member 46. The time required for this action depends upon the adjustment of the screw 55', as suming a given energizing current provided in the heating element 40.

The upstanding guide pin 26' engages slidably through the central aperture of a guide disc 101 of insulating mate rial snugly positioned in the top portion of shell 13. Thus, the relay assembly frame 21 is supported and slidablyretained at its top end, preventing cantilever movement thereofand enabling the assembly to withstand severe shock and vibration conditions without impairing its operation.

It will be noted that the assembly is automatically-compensated for variations in ambient temperature, since the strip 34-. is made of the same material as the supporting frame member 21.

As. will be readily apparent, heating elements 40 of different thermal masses will give correspondingly different time delays, in view of the different times required to bring the heating elements up to their operating temperatures..The larger the mass of the heating element 40, the longer will be required for it to reach its operating temperature. Thus, where a relatively short time delay is required, the heating element may be similar to that illustrated in FIGURE 2, namely, may comprise a strip of refractory material of small thermal mass on which the heater winding 61 is mounted, the supporting strip 60 being connected in anysuitable manner to the strip 34, being suitably insulated therefrom, but being inolose thermal contact therewith so as to deliverheat rapidly thereto. The arrangement of FIGURE 2 is such that the heating element defined by-the strip 60 and its winding 61 has a very small thermal mass and consequently, the heating element reaches its operating temperature in .a relatively short period of time, as compared with the encased heater 40 shown in FIGURE 1. I

As shown in FIGURE 4, the main frame portion of the relay, connected to the respective prongs 14, 15, 17 and 20, constitutes one terminal of the time-delayed switch, the other terminal comprising the prong 16. The arrangement thereby comprises a single-pole, single-throw switch of the normally open type. It will be noted, from FIGURE 3, that the contact-bar element 53 is offset forwardly so that it is normally disengaged from the contact button 47, allowing clearance for the button to move to the right, as viewed in FIGURE 3, to come into contact with the forwardly-offset bar 53. The shape of the contact bar may be suitably modified, as illustrated in FIGURE 5, so that the button 47 normally engages the bar, shown at 53', whereby the switch thus defined is of the normally closed type, the contact button 47 disengaging from the bar 53' with snap action at the predetermined time delay for energization of the heater element of the relay. Thus, in the arrangement of FIGURE 5, the button 47 engages the contact bar 53', said bar being located to the left of the button, namely, between the tongue 30 and the rear wall tab 35. The action is similar to, but reversed from that described above in connection with the normally open switch illustrated in FIGURES 3 and 4. FIGURE 6 shows the electrical Wiring diagram corresponding to the normally closed switch arrangement of FIGURE 5.

FIGURE 7 shows a further modification wherein the switch is arranged as a single-pole, double-throw switch. In this modification, the prong 20 is employed as the additional required contact terminal. The structure is similar to that shown in FIGURE 5, except that the supporting lug 39 is eliminated and that the additional contact bar, shown at 70, is secured to the upper end portion of prong 20, the contact bar 70 extending transversely and parallel to the contact bar 53', but on the opposite side of the contact button 47. In this arrangement shown in FIGURE '7, contact button 47 normally engages contact bar 53', but after the specified period of energization of the heating element of the relay, the button 47 suddenly disengages from the contact bar 53' and moves into engagement with the contact bar 70. The reverse action occurs upon the deenergization and cooling of the heating element.

In the modification shown in FIGURES 15, 16 and 17, the upstanding main supporting frame member, designated at 21', is generally similar in construction to the frame member 21 previously described, but the bottom portion of the frame member is secured in a vertical, generally U-shaped, upstanding bracket, shown at 80, having the rear end wall 81 and the respective sidewalls 82, 82. The end wall 81 is provided with an outwardly-extending fastening lug 83, and the sidewalls are likewise provided with outwardly-extending fastening lugs 84, 84. The lugs 83 and 84 are suitably apertured to receive fastening members 85 for securing the bracket 80 to a supporting surface. The lower portions of the side flanges 23' and 24' are suitably secured, as by welding, or the like, to the inside surfaces of the upstanding sidewalls 82, 82 of bracket 80. The rear wall 81 of the bracket is formed with a rectangular notch 85 and a rearwardly-extending vertical flange 86 on which is mounted a microswitch 87, the microswitch having the inwardly-projecting actuating plunger 88 which is located in the path of movement of the inner end of the operating screw 55 of the relay. As in the previously-described form of the invention, the frame member 21' is formed with the tongue member 30, the bottom tab 33 on the tongue member, and the upstanding flange 26 on the top arm 25, the strip 34 being connected between flange 26 and tab 33 in the same manner as previously-described, being placed under tension, and placingthe tongue 30 under compression. When the heating element is energized, after a specified time delay, the inner end of the screw 55 engages the plunger 88 of microswitch 87, operating the microswitch. Reverse operation occurs upon de-energization of heater 40 and cooling thereof.

As above-mentioned, an important feature of the form of the thermal time-dealy relay illustrated in FIGURES 1 to 14, .is the particular action of the snap-spring contact arm 46. The action of this arm is such that the contact pressure between the contact button 47 and the associated stationary contact increases up to the point where the spring arm snaps to its reverse condition, because of the building up of stress in the spring arm as the bowed actuating portion 50 thereof is engaged by the abutment screw 55. Thus, in the case of the normally open switch of FIGURE 1, the button 47 engages the stationary contact arm 53 with maximum force when the spring arm 46 snaps. In the case of the normally closed switch arrangement, of FIGURE 5, the contacting force on the stationary contact 53 increases up to the point of disengagement of the contact button 47 therefrom. In the case of the doublethrow switch arrangement of FIGURE 7, the contact button 47 engages the stationary contact arm 53' with maximum force at the point where the spring arm 46 snaps and engages the opposite contact arm 70 with maximum force. The use of the snap-acting spring arm 46 thus insures positive and clean switching action in the various embodiments illustrated above.

FIGURE 18 shows a modification similar to that of FIGURE 2, but wherein instead of using a toggle-action contact arrangement, a depending resilient spring metal contact blade 102 is secured by welding or the like, to tongue 30 and is provided at its bottom end with a contact button 47' engageable with stationary contact bar 53 after a time period of energization of heater winding 61 determined by the adjustment of screw 55. As shown in FIGURE 18, the screw 55 engages the depending portion of blade 102 and may be adjusted to flex said blade to establish a preliminary desired spacing of button 47' from contact bar 53.

FIGURE 19 shows an arrangement similar to that of FIGURE 18, except that the contact button 47 normally engages the left side surface of bar 53, whereby the switch contacts 47-53 are normally closed. The time period required for said contacts to open will be determined by the adjustment of screw 55, since said screw regulates the amount of flexural tension in the resilient blade 102. When sufficient heat has been generated by winding 61, screw 55 acts against blade 102 to move button 47 toward the left, as viewed in FIGURE 19, causing said button to disengage from contact bar 53.

While certain specific embodiments of an improved thermal-delay switch assembly have been disclosed in the fore-going description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore, it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is:

1. A thermal delay switch assembly comprising an upstanding elongated one-piece channel-shaped metal support, the web of said support being formed with an inwardly-pressed resilient tongue element extending from the top end portion of the web of the support toward the bottom end portion of said web, with an integral arcuate transversely inwardly-offset corrugation at the connection of the top end of the tongue element to the top end portion of the web, the tongue element being substantially housed at all times between the flanges of the support, a strip of the same metal as said support connecting the top end portion of the support to the bottom end portion of the tongue element and being suffici'ently short so that said tongue element is arcuatelybowed when the strip is in a cool. state, whereby in said cool state the tongue elem'ent is in compression and the,

operatively-engageable by said abutment means resp0n-' sive to the movement of said abutment means.

2. The delay switch assembly of claim 1', and wherein said abutment means comprises an adjustable screw memb'er'threadedly engaged through said connectedend portions and substantially aligned with said switch-actuating means. I

3. The delay switch assembly of claim 1', and wherein said one end portion of the support is provided witha connection flange projecting substantially at right angles to the web of the support, said strip being connected to said connection flange. I y

4. The delay switch assembly of claim 1, and wherein said switch means comprises a flexible switch arm and wherein said switch-actuating. means comprises a bowed spring element connected to the switch armtor flexing said arm with a snap action, said bowed spring element being in the path of movement of said abutment means,

8. and a stationary contact element mounted in a position to be engaged by said switch arm.

5. The delay switch assembly of claim 1, and wherein said switch means comprises a flexible switch arm secured at one end to the web of the support and wherein said switch-actuating means comprises a bowed spring element connected to the switch arm for flexing the arm with a snap action, said spring element being in the path of movement of said' abutment means, and spaced stationary contacts mounted on opposite sides of and being respectively engageable by said switch arm in the opposite conditions of flexure thereof.

6. The delay switch assembly of claim 1, and wherein said. switch means comprises a stationary snap switch having an operating plunger and being mounted so that the operating plunger is in the path of movement of said abutment means. 7

7. The delay switch assembly of claim 6, and wherein said abutment means comprises an adjustable screw member threaded in said connected end portions and being substantially aligned with said operating plunger.

References Cited UNITED STATES PATENTS 2,948,788 8/ 1960' Br'oekhuysen 2 00-122 2,65 8,975: 11/ 1953 Zuckerman 20'0122 2,961,516 11/1960 Broekhuyse'n 200122' BERNARD A. GI'LHEANY, Primary Examiner.

H. A. LEWITTER, Assistant Examiner. 

1. A THERMAL DELAY SWITCH ASSEMBLY COMPRISING AN UPSTANDING ELONGATED ONE-PIECE CHANNEL-SHAPED METAL SUPPORT, THE WEB OF SAID SUPPORT BEING FORMED WITH AN INWARDLY-PRESSED RESILIENT TONGUE ELEMENT EXTENDING FROM THE TOP END PORTION OF THE WEB OF THE SUPPORT TOWARD THE BOTTOM END PORTION OF SAID WEB, WITH AN INTEGRAL ARCUATE TRAVERSELY INWARDLY-OFFSET CORRUGATION AT THE CONNECTION OF THE TOP END OF THE TONGUE ELEMENT TO THE TOP END PORTION OF THE WEB, THE TONGUE ELEMENT BEING SUBSTANTIALLY HOUSED AT ALL TIMES BETWEEN THE FLANGES OF THE SUPPORT, A STRIP OF THE SAME METAL AS SAID SUPPORT CONNECTING THE TOP END PORTION OF THE SUPPORT TO THE BOTTOM END PORTION OF THE TONGUE ELEMENT AND BEING SUFFICIENTLY SHORT SO THAT SAID TONGUE ELEMENT IS ARCUATELYBOWED WHEN THE STRIP IS IN A COOL STATE, WHEREBY IN SAID COOL STATE THE TONGUE ELEMENT IS IN COMPRESSION AND THE STRIP IS IN TENSION, AN ELECTRIC HEATING ELEMENT MOUNTED ON SAID STRIP IN THERMAL CONTACT THEREWITH, WHEREBY WHEN THE HEATING ELEMENT IS ENERGIZED THE HEAT THEREFROM CAUSES THE STRIP TO EXPAND AND MOVE THE CONNECTED END PORTIONS OF THE STRIP AND TONGUE ELEMENT TOWARD THE WEB OF THE SUPPORT, ABUTMEMT MEANS ON SAID CONNECTED END PORTIONS, AND SWITCH MEANS MOUNTED ADJACENT SAID TONQUE ELEMENT AND BEING PROVIDED WITH SWITCH-ACTUATING MEANS OPERATIVELY-ENGAGEABLE BY SAID ABUTMENT MEANS RESPONSIVE TO THE MOVEMENT OF SAID ABUTMENT MEANS. 